/*
 * Created on 29-Jul-2004
 * Created by Paul Gardner
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 */

package org.gudy.azureus2.core3.tracker.server.impl;

/**
 * @author parg
 *
 */

import java.net.InetSocketAddress;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

import org.gudy.azureus2.core3.config.COConfigurationManager;
import org.gudy.azureus2.core3.config.ParameterListener;
import org.gudy.azureus2.core3.logging.LogEvent;
import org.gudy.azureus2.core3.logging.LogIDs;
import org.gudy.azureus2.core3.logging.Logger;
import org.gudy.azureus2.core3.tracker.server.TRTrackerServer;
import org.gudy.azureus2.core3.util.AEMonitor;
import org.gudy.azureus2.core3.util.AESemaphore;
import org.gudy.azureus2.core3.util.AEThread;
import org.gudy.azureus2.core3.util.Debug;
import org.gudy.azureus2.core3.util.ThreadPool;
import org.gudy.azureus2.core3.util.ThreadPoolTask;

import com.aelitis.azureus.core.proxy.AEProxyFactory;

public class TRTrackerServerNATChecker {
    private static final LogIDs LOGID = LogIDs.TRACKER;
    protected static TRTrackerServerNATChecker singleton = new TRTrackerServerNATChecker();

    protected static final int THREAD_POOL_SIZE = 32;
    protected static final int CHECK_QUEUE_LIMIT = 2048;

    protected static int check_timeout = TRTrackerServer.DEFAULT_NAT_CHECK_SECS * 1000;

    protected static TRTrackerServerNATChecker getSingleton() {
        return (singleton);
    }

    protected boolean enabled;
    protected ThreadPool thread_pool;

    protected List check_queue = new ArrayList();
    protected AESemaphore check_queue_sem = new AESemaphore("TracerServerNATChecker");
    protected AEMonitor check_queue_mon = new AEMonitor("TRTrackerServerNATChecker:Q");

    protected AEMonitor this_mon = new AEMonitor("TRTrackerServerNATChecker");

    protected TRTrackerServerNATChecker() {
        final String enable_param = "Tracker NAT Check Enable";
        final String timeout_param = "Tracker NAT Check Timeout";

        final String[] params = { enable_param, timeout_param };

        for (int i = 0; i < params.length; i++) {

            COConfigurationManager.addParameterListener(params[i], new ParameterListener() {
                public void parameterChanged(String parameter_name) {
                    checkConfig(enable_param, timeout_param);
                }
            });
        }

        checkConfig(enable_param, timeout_param);
    }

    protected boolean isEnabled() {
        return (enabled);
    }

    protected void checkConfig(String enable_param, String timeout_param) {
        try {
            this_mon.enter();

            enabled = COConfigurationManager.getBooleanParameter(enable_param);

            check_timeout = COConfigurationManager.getIntParameter(timeout_param) * 1000;

            if (check_timeout < 1000) {

                Debug.out("NAT check timeout too small - " + check_timeout);

                check_timeout = 1000;
            }

            if (thread_pool == null) {

                thread_pool = new ThreadPool("Tracker NAT Checker", THREAD_POOL_SIZE);

                thread_pool.setExecutionLimit(check_timeout);

                Thread dispatcher_thread = new AEThread("Tracker NAT Checker Dispatcher") {
                    public void runSupport() {
                        while (true) {

                            check_queue_sem.reserve();

                            ThreadPoolTask task;

                            try {
                                check_queue_mon.enter();

                                task = (ThreadPoolTask) check_queue.remove(0);
                            } finally {

                                check_queue_mon.exit();
                            }

                            try {
                                thread_pool.run(task);

                            } catch (Throwable e) {

                                Debug.printStackTrace(e);
                            }
                        }
                    }
                };

                dispatcher_thread.setDaemon(true);

                dispatcher_thread.start();

            } else {

                thread_pool.setExecutionLimit(check_timeout);
            }
        } finally {

            this_mon.exit();
        }
    }

    protected boolean addNATCheckRequest(final String host, final int port, final TRTrackerServerNatCheckerListener listener) {
        if ((!enabled) || thread_pool == null) {

            return (false);
        }

        try {
            check_queue_mon.enter();

            if (check_queue.size() > CHECK_QUEUE_LIMIT) {
                if (Logger.isEnabled())
                    Logger.log(new LogEvent(LOGID, LogEvent.LT_WARNING, "NAT Check queue size too large, check for '" + host + ":" + port
                            + "' skipped"));
                // Debug.out( "NAT Check queue size too large, check skipped" );

                listener.NATCheckComplete(true);

            } else {

                check_queue.add(new ThreadPoolTask() {
                    protected Socket socket;

                    public void runSupport() {
                        boolean ok = false;

                        try {
                            InetSocketAddress address = new InetSocketAddress(AEProxyFactory.getAddressMapper().internalise(host), port);

                            socket = new Socket();

                            socket.connect(address, check_timeout);

                            ok = true;

                            socket.close();

                            socket = null;

                        } catch (Throwable e) {

                        } finally {

                            listener.NATCheckComplete(ok);

                            if (socket != null) {

                                try {
                                    socket.close();

                                } catch (Throwable e) {
                                }
                            }
                        }
                    }

                    public void interruptTask() {
                        if (socket != null) {

                            try {
                                socket.close();

                            } catch (Throwable e) {
                            }
                        }
                    }
                });

                check_queue_sem.release();
            }
        } finally {

            check_queue_mon.exit();
        }

        return (true);
    }
}
